Polonium

Polonium, ₈₄Po

Polonium
Pronunciation	/pəˈloʊniəm/ ​(pə-LOH-nee-əm)
Appearance	sillery
Mass number	[209]
Polonium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Te ↑ Po ↓ Lv bismuth ← polonium → astatine
Atomic nummer (Z)	84
Group	group 16 (chalcogens)
Period	period 6
Block	p-block
Element category	Post-transeetion metal
Electron confeeguration	[Xe] 4f14 5d10 6s2 6p4
Electrons per shell	2, 8, 18, 32, 18, 6
Pheesical properties
Phase at STP	solit
Meltin pynt	527 K ​(254 °C, ​489 °F)
Bylin pynt	1235 K ​(962 °C, ​1764 °F)
Density (near r.t.)	(alpha) 9.196 g/cm3 (beta) 9.398 g/cm3
Heat o fusion	ca. 13 kJ/mol
Heat o vapourisation	102.91 kJ/mol
Molar heat capacity	26.4 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K)       (846) 1003 1236
Atomic properties
Oxidation states	−2, +2, +4, +5, +6 (an amphoteric oxide)
Electronegativity	Pauling scale: 2.0
Atomic radius	empirical: 168 pm
Covalent radius	140±4 pm
Van der Waals radius	197 pm
Spectral lines o polonium
Ither properties
Creestal structur	​cubic
Thermal expansion	23.5 µm/(m·K) (at 25 °C)
Thermal conductivity	? 20 W/(m·K)
Electrical resistivity	(α) 0.40 µ Ω·m (at 0 °C)
Magnetic orderin	nonmagnetic
CAS Nummer	7440-08-6
History
Diskivery	Pierre Curie an Marie Curie (1898)
First isolation	Willy Marckwald (1902)
Main isotopes o polonium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 208Po syn 2.898 y α 204Pb β+ 208Bi 209Po syn 103 y α 205Pb β+ 209Bi 210Po trace 138.376 d α 206Pb

Polonium is a chemical element wi the seembol Po an atomic nummer 84, discovered in 1898 bi Marie Curie an Pierre Curie. A rare an heichly radioactive element wi na stable isotopes, polonium is chemically seemilar tae bismuth an tellurium, an it occurs in uranium ores. Applications o polonium are few, an include heaters in space probes, antistatic devices, an soorces o neutrons an alpha particles. Acause o its poseetion in the periodic cairt, polonium is whiles clessifee'd as a metalloid. Ither soorces say that on the basis o its properties an behaviour, it is "unambiguously a metal".